Abstract

Importance

Abnormal reward processing is suggested to underlie the formation of psychotic symptoms, likely driven by elevated ventral striatal (VS) dopamine levels. Functional magnetic resonance imaging studies reveal alterations of VS activity during reward processing in patients with chronic psychosis and first episode of psychosis, as well as individuals at high risk for psychosis, but findings are inconclusive, conflicting, and difficult to subject to meta-analysis without introducing bias because several studies reported that findings were not statistically significant but did not report statistics.

Objective

To assess the differences between patients with schizophrenia spectrum disorders and healthy controls in VS activation during reward processing.

Data Sources

Web of Knowledge database (incorporating Web of Science and MEDLINE) until July 2015, including references of eligible articles and reviews.

Statistics and thresholds related to the main outcome measures and potential moderators were independently retrieved by 2 investigators. Effect sizes were analyzed using MetaNSUE, a random-effects method that enables the unbiased inclusion of nonstatistically significant unreported effects.

Main Outcomes and Measures

Effect size of the group differences in VS activity, and correlation between VS activity and negative and positive symptom scores in patients.

This meta-analysis provides evidence that patients with psychosis demonstrate VS hypoactivation during reward anticipation. The assessment of VS prediction errors seems to be promising, but more studies are needed to draw valid conclusions.